A DENT IN THE FOREHEAD 



Charles B. Davenport 



ONE of the most striking phe- 

 nomena to a student of heredity 

 is the definiteness with which 

 certain small, apparently in- 

 significant, peculiarities are inherited. 

 This is very prettily illustrated again 

 by a case which a correspondent has 

 sent to me and, although the family 

 history is only a fragment, it is so 

 instructive as to be worth publishing. 



The trait in question consists of a 

 small depression in the sagittal plane 

 of the frontal bone, extending two or 

 three centimeters above a line joining 

 the upper limits of the orbits. The 

 depression is a striking one, but the 

 morphological changes involved do not 

 seem to be great. Nevertheless they 

 are very persistent in the family history 

 and without doubt indicate a definite 

 modification of the germ plasm which 

 is, in accordance with the modern 

 interpretation, of the positive, dominant 

 sort; that is, due to the addition of a 

 gene. 



We start with a fraternity of three 

 grown children, born between 1885 and 

 1890 (III, 20-23). The first, a male, 

 has a deep dent in his forehead, as if 

 his skull were pushed in. This is the 

 young man whose photograph is pre- 

 sented herewith (Fig. 6). The second, 

 male, has a deep crease or dent in 

 forehead and the third, female, has a 

 crease in forehead. A fourth member 

 of the fraternity was a small boy who 

 died at the age of nine months and of 

 whom we have no description. The 

 father of this fraternity of three (II, 15) 

 had a dent in the forehead. The 

 mother (II, 14) was unrelated to the 

 father and none of her relatives had a 

 peculiarity of this sort. By another 

 wife the father had one daughter 

 (III, 24) who, likewise, had the crease 

 in the forehead. As this other wife 

 was unrelated and did not show the 

 crease in the forehead, this portion of 

 the pedigree, alone, is sufficient to 



suggest strongly that the joositivc trait 

 is carried in the germ ])lasm of the 

 father. 



The father was one of a fraternity of 

 seven, three males and four females. 

 One of his brothers (II, 5) showed the 

 same crease in the forehead. The other 

 did not. Three of the sisters certainly 

 have shown the crease in the forehead. 

 One of these is married and had six 

 children, one boy and five girls, and of 

 these girls three show the crease in the 

 forehead (III, 3-8). Of the fourth 

 sister of the father, long since dead 

 (III, 7), there are no precise data. In 

 response to an inquiry my correspondent 

 has examined a group photograph in 

 which the sister appears and replies: 

 "It is impossible to be sure, but I 

 think there was a slight trace of it 

 from what I could see." This fourth 

 sister has had four children (by three 

 husbands), and one (a son) shows the 

 crease in the forehead. The single 

 member of the second generation who 

 lacks the family trait has two children, 

 neither of whom has the trait ; however, 

 the same is true of the two children of 

 his sister (II, 1) who has the trait. 

 Unfortunately definite knowledge is 

 extant concerning two generations only. 

 The conditions in the grandparents are 

 unknown. So far, then, as our informa- 

 tion goes it indicates that this slight 

 family peculiarity in the form of the 

 frontal bone of the skull is inherited 

 as a dominant trait. 



In conclusion the writer wishes first 

 to thank Miss Rose M. Dawson for her 

 cooperation and, second, to request 

 those in whose family such (or other 

 clearly marked) peculiarity in the form 

 of the skull, appears, or who know of 

 such a family trait among their ac- 

 quaintances, to communicate the fact 

 to him. 



Carnegie Institution of Washington, Station 

 for Experimental Evolution, Cold Spring Har- 

 bor, Long Island, N. Y., Jan. 30, lOl.v 



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